Optical pickup and optical read/write drive
a pickup and optical technology, applied in the field of optical pickup and optical read/write drive, can solve the problems of difficult to read data as intended, difficult to increase the write rate, and deformation of the recorded mark, and achieve the effect of good stability and good quality
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embodiment 1
[0107]Hereinafter, an optical pickup as a first specific preferred embodiment of the present invention will be described.
[0108]FIG. 5 illustrates the arrangement of an optical system for the optical pickup as the first preferred embodiment of the present invention. This optical pickup includes a laser light source 1, an optical modulator 9 for use to leave a signal mark on an optical storage medium 6, a diffractive element 2 that diffracts the light that has come from the laser light source 1 and splits it into a zero-order light beam and ±first-order light beams, a condenser lens 5 that condenses those diffracted light beams onto the optical storage medium 6, and a photodetector 8 that receives the light beams that have been reflected from the optical storage medium 6. With this optical pickup, while a write operation is being performed using the light beam spot formed by the zero-order light beam, a read signal can also be obtained by calculating the difference between the signals...
embodiment 2
[0133]Next, an optical pickup as a second preferred embodiment of the present invention will be described.
[0134]FIGS. 10 and 11 are respectively a plan view and a cross-sectional view illustrating a configuration for two diffractive elements 20 and 21 for use in an optical pickup according to this second preferred embodiment.
[0135]As shown in FIG. 10, the grating vectors of the two diffractive elements 20 and 21 have mutually different directions and magnitudes.
[0136]The grating vector of the diffractive element 21 agrees with the Y direction. On the other hand, the grating vector of the diffractive element 20 slightly tilts toward the X direction from the Y direction, and has a smaller grating vector (i.e., a smaller grating pitch) than the diffractive element 21.
[0137]Since those two elements 20 and 21 are stacked one upon the other as shown in FIG. 11, the light beam 100 that has been emitted from the light source first gets diffracted and split in the Y direction by the diffract...
embodiment 3
[0142]Next, an optical pickup as a third preferred embodiment of the present invention will be described.
[0143]FIG. 13(a) is a plan view illustrating a configuration for a diffractive element 30 for use in the optical pickup of this preferred embodiment. The diffractive element 30 of this preferred embodiment is divided into multiple slips in the Y direction, i.e., in the tangential direction, so that two different gratings A2 and B2 are arranged alternately in the diffractive element 30.
[0144]The grating vector of the grating A2 agrees with the Y direction and is uniform in the grating. On the other hand, the grating vector of the grating B2 has a distribution of directions. And the light that has been diffracted by the grating B is given an aberration. A zero-order light beam, however, is not given an aberration due to the distribution of grating vectors even when transmitted through the grating B2.
[0145]FIG. 13(b) is a cross-sectional view of the diffractive element 30. As the di...
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Abstract
Description
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